Alright: got a new update for my quest!
so uhh, I've finally finished my quest to make Jeff ABSOLUTELY SAD by beating the game with all characters on hard diff. I've found a discovery that when Jeff is almost at no health, he shoots himself. Yeah. Btw, a firework display occurred while doing the last character in the Jeff's bossfight, interacted with the glitching dead dude, boom, blue n red. Even Jeff himself tried to do it XD . 10/10.